US2338573A - Catalytically processing hydrocarbon oils - Google Patents

Description

Jan. 4,1944.- G. D. CREELMAN CATALYTICALLY PROCESSING HYDROCARBON OILS Filed Sept. 13, 1939 INVENTOR CeayeG/leeman my kATTORNEY Patented Jan. 4, 1944 CATALYTICALLY PROCESSNG HYDRO- Y CARBON OILS George D. Creelman, Mountain Lakes, N. J., as signor to The M. W. Kellogg Co., Jersey City,

. N. J., a corporation of Delaware i y 'Application September 1^3, 1939, Serial 14 Claims.

'I'his invention relates'to a process of converty.ing aliphatic, .open-chain hydrocarbons and naphthenic hydrocarbons into aromatic hydrocarbons by a process of dehydrocyclization. Open-chain hydrocarbons having more than six carbon atoms are simultaneously dehydrogenated designed to provide forma more uniform conversion, in a unitary process, of the open-chain hyand formed into aromatic -ring compounds and naphthenic hydrocarbons are-further dehydrovgenated in the process into aromatic hydrocarbons. An object of the invention is to convert the hydrocarbons of petroleum naphthas into .aromatic motor fuels of. high knock rating.

Naphthas of various boiling ranges may bel emtinent or East Texas naphthas having a boiling range of about 250 to 450 F. are suitable, or a to 500 F. Y

A further objectv of the processis to convert low knock rating gasoline and naphthas into high ployed. For example, Pennsylvania, Mid-Conknock rating aromatic type motor fuels by passing the vapors of the naphthas in contact with an petroleum may be introduced byline I0 into fracaromatizing catalyst maintained at an average temperature of about 875 to 1075 F. and more per square hinch `gauge andI prefer to employ pressures of about 150 to 250 'poundsper square inch. It is also important to employ in the con.

amount ranging from about 0.4 to 8 mol ratio of.. so f hydrogen tohydrocarbon treated. In a typicaL case, I may employ a mol ratio of 2 to .hydrogen per mol of hydrocarbon.

YIt isan important feature and object of s, process to regulate the time of contact between the catalyst and the hydrocarbon in a specific drocarbons, both light and heavy, into aromatics.

The time of contact employed in my process may be expressed as the time factor which term is employed 'to mean the timelinfhours required for one volume of naphtha charged in the process to flow through one apparent volume of porous catalyst. The time factors which I prefer to employ lie within the range of`0.1 or'0.2 to 25,

"'dependingon. the fraction of the oil under consideration, and a time factor of `1 to 2 hours per volume per volume is typical of the operating conditions employed with naphtha of intermedate boiling range. v f

My process is illustrated by means of drawing in which Figure l represents diagrammatically a scheme for continuously treating petroleum naphthas byl means of a moving bed catalyst which is continuously removed for regeneration and renewal. Figure 2 'represents an alternative arrangement of catalyst chambers in which the catalyst is maintained in fixed beds and is regenerated in situ. Referring to Figure 1 of the draw.. lng, crude petroleum or a distillate from crude tionator li equipped with the usual bubble plates or'equivalent fractionating means (not shown) .together with a reboiling coil i2 and reflux coil I3. There may be'two or more fractions, for example, fourfractions, .of naphthas as previously described generally boiling within the range of tacting step of my process, hydrogen or hydrogencontaining gas, the hydrogen being present in an *Y manner, vand a principal object of my invention is tosubdivide the naphtha or gasoline undergoing treatment into two or more fractions of different boiling points and to subject the lighter fractions x to a longer time of contact in the same operation vwith the other fractions. I have discovered that those hydrocarbons of highermolecular Weight are advantageously subjected to a shorter time of contact than provided for the hydrocarbons of lower molecular weight. The heavier' hydrocarbons are more readily convertedA into aromatic hydrocarbons than are the lightlhydrocarbons and with excessive treatment, they tend to produce carbon and foul the catalyst. My process is 150 to 500F.

Progressively heavier naphtha fractions may be .withdrawn by side draws I4, l5, IS and Il and these may be subjected to. stripping by means not .lshownz z These naphtha fractions are then vaporin separate coils in furnace I8 and heated therein to a suitable conversion temperature. for

example, 975 F. .All fractions may be heated to the same temperature .but there is often an ad- "vantage to heating the separate fractions to a .different extent. Thus, the lightest fraction from withinthe catalyst chamber for introducing the il may be heated. to 1025 F. and introduced by line |9- into the upper. end of catalyst chamber 20, baillev 2i being provided to maintain-a space The next naphtha fraction from l5 may be heated in furnace I8 to a temperature of 1000 F. and then conducted by line 2,2 into catalyst chamber 20 at a later point. The next fraction from I6 may be heated to a .still lower temperature, for example 975 F., and introduced by line 23 into chamber 20.' The last fraction-from -l'l longer time of contact between the catalyst and the vapors of the lighter hydrocarbons. Positive control of the temperature throughout the elongated reaction chamber is also facilitated. As previously indicated, however, al1 fractions may be charged to the catalyst chamber at the same temperature, although it is usually desirable to` employ progressively higher temperatures with the light fractionshin which case the endothermic heat of conversion will produce a gradually diminishing temperature progressively through the reaction chamber 2li.

'I'he hydrocarbon vapors in catalyst chamber 20 are conducted therefrom by line 25 leading to condenser 25 and separating drum 21 where iixed gases, including hydrogen, are withdrawn byline 28 and the liquid products are withdrawn by line 29. The iixed gases comprising principally hydrogen and methane with C: and Ca hydrocarbons are conducted by line 28 to a heating coil 29 and thence by line 30 to the upper I end of reaction chamber 2D. The hydrogen present in the gases facilitates the catalytic reaction apparently by acting on intermediate hydrocarbon products on the surface of the catalyst and preventing their accumulation with consequent loss of catalytic'actlvity. Under the conditions employed, as previously outlined, substantially no hydrogenation of the naphtha occurs, as evidenced by the fact that the products obtained from the process are highly aromatic. For example, the products may contain 40 to 60% or ,more of aromatic hydrocarbons, including benzene, toluene, and the xylenes, togetherwith ethyl benzene and similar derivatives of benzene.

When the amount of hydrogen in the recycle gases is insufficient to accomplish the foregoing purpose lor the concentration becomes too low, I may add hydrogen through inlet 3|. If desired, the hydrogen may be obtained by purifying gas withdrawn from 32. Excess gases accumulating in the system beyond the amount necessary for recycling may be continuously or .intermittently discarded through drawof! line,

32. In nearly al1 cases., there will be a' net overt f all production of hydrogen.

wThe operation ot'catalyst chamber 20 is sub- -stantiallv as shown. The catalyst in the form of a granularv free-flowing solid is introduced through hopper 33 connected by valve 34 to the 'upper end of chamber 20.

` yoperated continuously or intermittently and Valve 34 may be serves to regulate the rate of flow of catalyst into the chamber 20 while simultaneously preventing the escape of hydrocarbon vapors from said chamber. Chamber 20 is maintained substantially i'ull of catalyst which is permitted to ,4 flow through thechamber continuously or intermittently by operating discharge valve 35. Valve 35 may be la vibrating or tipping plate beneath the catalyst discharge spout 35. As the catalystfiows downwardly through the elongated chamber 20, it is directed by batlles 2| to the center of the chamber and thence again to the walls of the chamber, thereby providing the desired amount of mixing of the catalyst and maintaining. a more uniformly vapor resistant bed. At lthe same time baiiies 2| maintain annular spaces within the catalyst chamber into which the hydrocarbon vapors are introduced as hereinbefore described. As the catalyst proceeds downwardly through the chamber concurrently with the hydrocarbon vapors subjected to treating, it becomes increasingly deactivated, partly as the result of the deposition of carbonaceous matter thereon. The most nearly deactivated catalyst at the bottom of the reaction chamber is sufficiently active to effect conversion of the heavier hydrocarbon fractions introduced by line 24 whereas the freshest and most active catalyst at the top of chamber 20 is available for converting the lighter naphtha introduced therein. 'lhe ratio of hydrogen gas to hydrocarbon oil treated is also the maximum at the in my process and an apparatus adapted to this purpose is partly illustrated in Figure 2 by lines 40, 39, 38, and 31, corresponding respectively to lines I9, 22, 23 and 24 in Figure l. In the fixed bed the -catalyst is preferably maintained in a series of interconnected chambers 4|, 42, 43 and 44. The vapors entering through 31 pass through chamber 4| and thence by line 45 to chamber 42. A fter leaving chamber 42 the vapors are further conducted by line 46 to chamber 43. Thence the vapors are further ,conducted by line v41 to chamber u. Teef-etonverted vapors vfrom chamber 44 are withdrawn by line 48 to gasoline recovery means not shown. Thus, the lightest naphtha fraction is introduced by line 40, the next heavier fraction by line 38, the next by line 38 and the heaviest by line 31. It will be observed, therefore, that the lightest fraction introduced by line 40 is sub- :lected to the longest path through the catalyst and hence to the greatest catalyst treating time.

After the catalyst has become exhausted in the reaction chambers 4| to 44, theilow of .hydrocarbon vapors is interrupted and the vapors are chambers 4| to 44 is still hot, it may be regenremoved from the catalyst chambers by a current of steamA or inert gas.4 While the catalyst in erated by. introducing an oxygen-containing gas,

. For example, air or-air-inert gasI mixtures, such vas air and nitrogen or air and ue gas may be introduced by header 50 leading to valved lines 5|, 52, 53 and 54, which supply the oxidizing gas in the desired amount to the catalyst in the reaction chambers. The oxygen combines with and removes the carbon deposited on the catalyst as carbon dioxide and carbon monoxide which escapethrough lines 55, 56, 51'and 58. The rate of introduction of air and the oxygen concentration therein must be controlled during the regeneration operation to prevent excessive generated and allowed to cool to the desired reaction temperature, the process rearrangement is repeated.

of hydrocarbon lposition.

The catalysts which! prefer to employ in my process are the oxides of metals iny the left columns of'g'roups IV, V vand VI of the periodic systemv of elements. For example, I may employ oxides of chromium, molybdenum, tungsten, vanadium, titanium, cerium, thorium, etc. In general, I prefer to employ these oxides distributed on a supporting materialsuch as certain ofthe natural aluminous earths, bauxite, aluminum oxide and particularly aluminum oxide gel prepared from the relatively pure aluminum hydroxide` by methods'which provide a support having'an extensive surface. The oxides of chromium, etc., hereinabove mentioned, may be deposited on the alumina by various means, for example by impregnating the alumina with solutions of the nitrates, followed by thermal decom- Ammonium chromate, ammonium vanadate and similar ammonium salts may also 'be employed in solution as a means of 'applying the desired oxide, either singly or in combination, to the alumina support. The amount of catalyst oxide employed may suitably be about 1 to 10% and typically 5% is a satisfactory amount. The resulting catalyst may be pelleted or extruded to produce the desired porous form for use in the catalyst chambers. When excessive disintegration'oi'l the catalyst to powder occurs in use, it is desirable to remove it and separate the disintegrated material to prevent excessive back pressure in the catalyst bed. Although regeneration temperatures of 1000 to 1100 F. have been mentioned hereinabove, some oxidecatalysts may be heated to considerably higher temperatures without material loss of catalyticactivity. For example, cerium and thorium oxides on alumina may-.bemegenerated at temperatures as Yhigh as 1400 to 1600* F. Intermediate temperatures of 1200 to 1300" F. aresatisfactory for different catalysts, depending on their particular composition.

As an exampleof the results obtainable by my process, I may process a Mid-Continent heavy naphtha of to 55 octane number C. F. Rl motor -process possess knock ratings within the range of '75 to 85 octane number C. F. R. motor method and excellent motor fuels having knock ratings of the conversionof said combined llghterfractlons and heavier fractions, withdrawing the combined vapors of lighter` and heavier naphtha fractions from said conversion zone, and condensing and separating liquid motor fuel products from hydrogenous gases associated therewith.

2. The method of aromatizing petroleumnaphtha which comprises fractionating said naphtha into lighter and heavier fractions, vseparately heating the fractions to a high conversion temperature above 875 F., contacting the vlighter fractions with a solid aromatizing catalyst' in an elongated conversion zone in the presence of hydrogen under non-hydrogenating conditions,

commingling the vapors of said heavier fractions in said conversion zone with the vapors of said lighter fractions and catalyst after said lighter fractions have undergone substantial conversion by the action of said catalyst, continuing the conversion of said combined lighter fractions and heavier fractions, meanwhile causing said catalyst to flow concurrently through said zone with vapors of said naphtha fractions whilesaid fractions are undergoing conversion, withdrawing the combined vapors of lighter andheavier naphtha fractions from said conversion zone, and condensing and separating liquid motor fuel products from hydrogenous gases associated therewith.

3. In a process for converting open-chain hydrocarbons of petroleum naphtha into aromatic hydrocarbons useful for the production of motor fuel of high knock rating wherein vapors of pe- A fractionating said naphtha into lighter and heavier fractions before subjecting it to the action of said catalyst, disposing said catalyst in an extended path through which said hydrocarbon vapors are conducted, conducting said lighter fractionthrough the full extent of said vapor path, conducting said heavier fraction through a lesser extent of said vapor path wherein it is commingled with said light fraction, withdrawing .the commingled vapors of the lighter and heavier fractions-'from said catalyst and separating a about 80 C. F. R. motor method are readily obtained in good yield when processing paraillnic stocks such as Pennsylvania or Michigan naphthas which possess extremely low knock ratings before processing.

Having thus described my invention Awhat I claim is: Y

1. The method of aromatizing petroleum naphtha which comprises fractionating said naphtha into lighter and heavier fractions, separately heating the fractions to a high conversion temperature above 875 F., contacting the lighter fractions with a solid aromatizing catalyst in an elongated conversion zone in the presence of hydrogen under non-hydrogenating conditions, commingling the vapors of said heavier fractions in said conversion zone with the vapors of said lighter fractions and with catalyst after said lighter fractions have undergone substantial conversion by the action of said catalyst, continuing .naphtha fraction'is heated to a different temperature than that to which said heavier naphtha fraction is heated.

7. The process of obtaining more uniform aromatization of the constituents of petroleum naphtha subjected to the action of a solid arov matizing catalyst at an elevated temperature above 875 F. in the presence of hydrogen, comprising separating lighter hydrocarbons from heavier hydrocarbon constituents of said naphtha, subjecting said lighter hydrocarbons to an initial aromatization with said catalyst, commingling the vapors of said heavier hydrocarbons with said lighter hydrocarbons following said preliminary treatment, contacting said commingled hydrocarbons with additional catalyst. removing said hydrocarbons from said catalyst and recovering the desired aromatic hydrocarbon motor fuel therefrom.

8. VIn a process for convertingv an aliphatic hydrocarbon oil into high knock rating aromatic type gasoline wherein said oil is vaporized and the vapors are subjected, in the presence of added hydrogen, to the action of a porous solid dehydro' genating and cyclizing catalyst in a 'vertically ing and heating the vapors of said fractions to the desired temperature, introducing the lightest of said fractions into contact with the fresh catalyst in the upper part of said reaction zone and introducing successively heavier fractions at successively'lower points in said reaction zone, withdrawing the combined vapors of said fractions from the bottom of said reaction zone and separating from them the desired aromatic gasoline.

v9. The process of claim 8 wherein hydrogen is introduced into said reaction zone in contact with troducing said lightest fraction.

10. The process of claim 8 wherein-hydrogenous gases are separated from said reaction" products and recycled to said reaction zone. o

11. A method of catalytically aromatizing hy-l drocarbon naphtha which comprises initiallycontacting a light naphtha fraction with an aroma- 30 the fresh catalyst at a point above the point of inence of added hydrogen, the improvement which lytic aromatization of the constituents of a hyu drocarbon naphtha which comprises separating.

relatively light hydrocarbon constituents of e naphtha from the remainder and catalyticaily aromatizing them, recombining remaining constituents with said lighter constituents after the a vaporized heavier naphtha fraction into said' zone at a point intermediate the path of said light fraction therethrough, and causing. said heavier naphtha vapors to flow concurrently and in ad i mixture with said light vapors while contacting said catalyst vto promote the aromati'zation of bothoi" said fractions.

v1am a method of cataiyncanyaiiauzmg hydrocarbon naphtha-in the vapor phase at a temperature between about 875 and 1050 F. under superatmospheric pressure and in the prescomprises causing a vvaporized light' naphtha fraction-to flow through an elongated'connned the partially alromatized light fractionland subjecting the mixture to further contact" with an aromatizing catalyst under -aromatizing lconditions to complete the desired aromatizatio'n `ferm,lima- -f ..."f

zone in contact withan aromatizing catalyst maintained under said aromatizing conditions to effect aromatization of'said light fraction, causing said aromatizing catalyst to move through said zone concurrently with said light fraction.

introducing a vaporized heavier naphtha fraction into said zone at a point intermediate ther path of said light fractiontherethrough, and causing said,v

heavier naphtha vapors to now concurrently and in admixture with said light vapors `while contacting said catalyst-to promote the aromatization Tof both of-said fractions. f

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